The present invention relates to waste water treatment generally and more particularly to the use of biofilm supports.
The following U.S. Pat. Nos. are believed to represent the current state of the art: U.S. Pat. Nos. 5,980,738; 5,981,272; 5,985,148; 5,993,650; 6,063,268; 6,156,204; 5,948,262; 5,871,674; 5,783,066; 5,783,069; 6,126,829; 5,543,039; 5,458,779; 5,486,292; 4,985,182; 4,333,893; 5,217,616; 4,814,085; 4,814,125; 4,842,920; 5,168,058; 4,385,988; 4,522,767; 4,537,731.
The present invention seeks to provide an improved biofilm support as well as an improved waste water treatment system and methodology using the biofilm support.
There is thus provided, in accordance with a preferred embodiment of the present invention, a biofilm support, including a plastic biofilm support element having a maximum dimension which does not exceed 50 mm and having a specific gravity of between approximately 0.70-0.91.
There is additionally provided, in accordance with a preferred embodiment of the present invention, a biofilm support, including a plastic biofilm support element having a generally cylindrical configuration and including a plurality of radially extending surfaces extending outwardly from a generally solid center.
There is further provided, in accordance with a preferred embodiment of the present invention, a biofilm support, including a unitary plastic biofilm support element having a maximum dimension which does not exceed 50 mm and includes a plurality of roughened biofilm adherence surfaces integrally formed as one piece therewith.
There is still further provided, in accordance with a preferred embodiment of the present invention, a waste water treatment system, including a basin, at least one airlift operating in the basin and a multiplicity of plastic biofilm support elements, having any of the above characteristics, disposed in the basin for cooperation with the airlift.
There is yet further provided, in accordance with a preferred embodiment of the present invention, a method of manufacturing a plastic biofilm support element including:
extruding a plastic material mixed with a foaming agent to produce an elongate extruded plastic material having a specific gravity of between approximately 0.70-0.91;
cooling the elongate extruded plastic material; and
cutting the elongate extruded plastic material to have a maximum dimension which does not exceed 50 mm.
There is additionally provided, in accordance with a preferred embodiment of the present invention, a method of manufacturing a plastic biofilm support element including:
extruding a plastic material mixed with a foaming agent to produce an elongate extruded plastic material having a generally cylindrical configuration and including a plurality of radially extending surfaces extending outwardly from a generally solid center;
cooling the elongate extruded plastic material; and
cutting the elongate extruded plastic material to have a maximum dimension which does not exceed 50 mm.
There is yet additionally provided, in accordance with a preferred embodiment of the present invention, a method of manufacturing a plastic biofilm support element including:
extruding a plastic material mixed with a foaming agent to produce an elongate extruded plastic material having a plurality of roughened biofilm adherence surfaces integrally formed as one piece therewith;
cooling the elongate extruded plastic material; and
cutting the elongate extruded plastic material to have a maximum dimension which does not exceed 50 mm.
Preferably, the plastic biofilm support element has a generally cylindrical configuration and includes a plurality of radially extending surfaces extending outwardly from a generally solid center.
In accordance with a preferred embodiment of the present invention, the plastic biofilm support element has a plurality of roughened biofilm adherence surfaces integrally formed as one piece therewith.
Preferably, the plurality of radially extending ribs includes between 5 and 9 ribs.
In accordance with a preferred embodiment of the present invention, each of the plurality of ribs has a thickness of between 0.5 and 2 mm.
Preferably, the plastic biofilm support element includes a strip extending along an outwardly facing edge of each of the radially extending ribs.
In accordance with a preferred embodiment of the present invention, the plastic biofilm support element is formed of a plastic material selected from the following plastic materials: polyolefin, polystyrene, polyvinyl chloride and polyurethane.
Preferably, the plastic biofilm support element is formed of a plastic material mixed with a foaming agent.
In accordance with a preferred embodiment of the present invention, the plurality of ribs and the strips are configured so as to prevent interdigitation between ribs of two separate biofilm support elements.
Preferably, the support is configured so as to prevent mechanically retained joining of two separate biofilm support elements.
Preferably, the plastic biofilm support element has a specific gravity of between approximately 0.75-0.89 and more preferably between approximately 0.81-0.87.
In accordance with a preferred embodiment of the present invention, the roughened biofilm adherence surfaces have a roughness average (Ra) in the range of 100-800 microns and more preferably in the range of 200-500 microns.
Preferably, the plurality of radially extending surfaces are defined by a plurality of radially extending ribs.